Filtek Silorane Research Articles

Comparison of Various Properties of a Silorane Based Dental Composite with Two Methacrylate Based Dental Composites

AbstractThe synthesis of a new monomer system named silorane (obtained from the reaction of oxirane and siloxane molecules) gave way to the production of a novel low shrinkage silorane based composite. Objectives: The purpose of this study was to compare some physical properties of a silorane based composite (Filtek Silorane, 3MESPE) to those of two well-known low shrinkage methacrylate-based composites (Filtek Supreme XT, 3MESPE; Esthet X HD, Dentsply). The study also includes the effect of external media (food simulating solutions; distilled water, artificial saliva, 25% ethanol, coconut oil and Coke) on the three composites. Methods: Cured samples underwent water absorption (with immersion in food simulating solutions) and desorption. The data were analysed; the water absorption and desorption profiles were mapped, the diffusion coefficients and solubility of each sample were calculated. Curing efficiency was measured on the top and bottom surfaces of cured composite samples using Fourier Transform Infrared (FTIR) spectroscopy. Finally, the temperature profile during polymerisation of each composite sample was mapped, allowing the calculation of the sample‘s maximum exotherm. Results: From the results obtained from these experiments, overall, the properties of Filtek Silorane are comparable with those of Filtek Supreme XT and Esthet X HD.

Incremental layer shear bond strength of low-shrinkage resin composites under different bonding conditions.

The purpose of this study was to determine the incremental shear bond strength of a silorane-based composite (Filtek Silorane) repaired with silorane or a methacrylate-based composite (Filtek Z250) under various aging conditions. Also, the incremental bond strength of the silorane-based composite was compared with that of another low-shrinkage methacrylate-based composite (Aelite LS Posterior) under fresh and aged conditions, with and without the use of an adhesive resin between successive layers. The two brands of low-shrinkage composites were compared with a microhybrid, Filtek Z250, which served as the control. Substrate discs were fabricated and second layers were adhered to them immediately, after two weeks of aging, or after four weeks of aging and with and without an adhesive resin. Shear bond strengths were measured and failure modes were evaluated. The incremental bond strength of silorane to the silorane-based composite was not significantly different from that of the methacrylate-based composite. However, repairing a silorane-based composite with a methacrylate-based composite significantly reduced the bond strength. Aelite showed a lower incremental bond strength than Z250 and silorane, but the use of an adhesive significantly improved the bond strength. The absence of an oxygen-inhibited layer did not affect the bond strength of the consecutive layers of the silorane-based composite.

Interfacial integrity of low-shrinkage composite restorations related to the filling technique and consistency

Purpose: To evaluate the influence of filling techniques and consistency of low-shrinkage composites on the bond strength and internal gap formation in Class I bonded restorations. Two low-shrinkage restorative systems (N’Durance/Septodont and Filtek Silorane/3M ESPE) were used to restore Class I preparations. Bulk increment, two oblique increments or two horizontal increments were performed and Filtek Z350XT was used as a control. Each increment was photoactivated for 40 s and the restored teeth were then stored for 24 h at 37 °C before being longitudinally sectioned and the internal margins of the restorations dyed with 1% acid-red propylene glycol solution for 20 s. The specimens were water rinsed and digital images were recorded for the internal gap formation (%) analysis. Stick-shaped specimens were also tested in tension to evaluate the bond strength. Comparative consistency of unset composites was also performed. N’Durance exhibited the highest incidence of internal gaps amongst all the filling techniques. Filtek Silorane showed no significant difference of internal gap formation in comparison with Filtek Z350XT, regardless of the filling technique. Filtek Z350XT exhibited the highest bond strength and N’Durance the lowest when horizontally applied; bond strength of Filtek Silorane was not influenced by the filling technique. Both Filtek Z350XT and N’Durance presented lower consistency. Low-shrinkage composites seem to present equivalent or inferior bond strength and internal gap formation when compared to the methacrylate composite. The quality of the Class I preparation is dependent on the material and filling techniques.

Free radical entrapment and crystallinity of resin composites after accelerated aging as a function of the expiration date

This study evaluated the spin concentration and the crystallinity in different classifications of dental composites as a function of the material condition (new, aged and expired). Specimens were obtained according to the factors: composites: Filtek P60, Filtek Z250, Filtek Z350XT, and Filtek Silorane; and material conditions: new, aged, and expired. The syringe composites underwent an accelerated aging protocol (Arrhenius model). The magnetic properties of the composites were characterized using Electron Paramagnetic Resonance (EPR) and the concentration of spins (number of spins/mass) was calculated. The crystallinity of the composites tested was characterized with X-ray diffraction (XRD). Filtek P60 and Filtek Z250 presented similarities in terms of spin concentration and crystallinity, irrespective of the material condition. The aging protocol influenced the composite Filtek Z350XT that exhibited a significant increase in the spin concentration. Besides, lower intensity peaks of the organic matrix and amorphous silica were also observed for both aged and expired Filtek Z350XT. Although a significant lower spin concentration was observed for the silorane composite in comparison to that of the methacrylates, a decrease in the relative intensity of peaks of the amorphous region related to the organic components in the diffractograms was observed. The material conditions tested influence the crystallinity and the magnetic properties of the composites evaluated.

Resin composite characterizations following a simplified protocol of accelerated aging as a function of the expiration date

This study evaluated the mechanical, thermal, and morphological characteristics of different classifications of dental composites as a function of the material condition (new, aged and expired). Specimens were obtained according to these factors: Composites: Filtek P60, Filtek Z250, Filtek Z350XT, and Filtek Silorane; and Material conditions: new, aged, and expired. The syringe composites underwent an accelerated aging protocol (Arrhenius model). The flexural strength (FS) and flexural modulus (E) were obtained. The thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were also performed and the glass transition temperature (Tg) and the weight loss calculated. Topographic analysis of the composites was performed under SEM. The material conditions influenced the mechanical properties of the composites. The silorane composite exhibited a characteristic thermal behavior different from that of the methacrylates. In general, the Tg increased after the accelerated aging protocol and decreased for expired ones, compared to the new composites. A significant increase in FS of Filtek Z350XT after aging was accompanied by an increase in the Tg. The filler packings were in accordance with the manufacture׳s information. The topographic aspects of the composites were modified as a function of the material condition. The mechanical properties of the composites following a simplified protocol of accelerated aging varied as a function of the expiration date. The silorane composite presented a characteristic thermal behavior. Although the dental manufacturers may not be able to control variables as storage temperature and transportation conditions, these effects on the composite clinical performance can be minimized if properly considered.

Polymerization efficiency and flexural strength of low-stress restorative composites

ObjectivesTo assess depth of cure (DOC), degree of conversion (DC), and flexural strength (FS) of several resin composites with low-stress behavior. MethodsSonicFill (Kerr), SureFil® SDR™ (Dentsply), everX Posterior (GC), Kalore (GC), and Filtek Silorane (3M ESPE) were tested. DOC was measured with the Acetone Shake test. DC was assessed with Fourier Transform Infra-Red spectroscopy on top and at the bottom of 4mm-thick disk-shaped specimens. Bottom to top ratios of DC percentages were calculated. FS was evaluated with the Three-Point Bending test. DOC, DC, and FS data were statistically analyzed. ResultsSureFil® SDR™ and everX Posterior achieved significantly greater DOC than Kalore and Filtek Silorane. Also, SonicFill had significantly greater DOC than Filtek Silorane. Mean top DCs ranged between 71.46% and 52.44%. Kalore and everX Posterior had significantly lower top DCs than the other materials. Mean DC values at 4mm ranged largely from 57.95% to 6.82%. Kalore and Filtek Silorane had the lowest values of bottom DC and the difference was statistically significant. EverX Posterior and SonicFill recorded significantly higher FSs than the other materials. SignificanceSureFil® SDR™ and everX Posterior exhibited DOC over 4mm, the maximum thickness recommended for bulk placement, while SonicFill recorded DOC values very close to the 4mm threshold. SonicFill achieved the highest DC at the irradiated surface, as well as at 4mm depth. SureFil® SDR™ demonstrated similarly uniform curing through the bulk increment. All the tested composites complied with the requirements of FS established by ISO 4049/2009.

One year clinical follow up of a silorane-based versus a methacrylate-based composite resin

PurposeTo report one year clinical performance of two types of composite (silorane based versus methacrylate based) in class I preparations. Materials and methodsA total of 15 patients (9 female and 6 male aged 20–40 years) participated in this study where 30 class I cavities were restored with either Filtek silorane (P90) or a methacrylate based composite (Tetric EvoCeram) representing two main groups (n = 15). Each patient received at least one pair of restoration. The cavity design was restricted to eliminate primary carious lesions. All restorations were subjected to a clinical follow up schedule representing (baseline, 6 months and 12 months) during which, two investigators rated the restorations according to the modified USPHS criteria evaluating marginal integrity, surface roughness, marginal discoloration, color match, anatomic form (wear), recurrent caries, retention of restoration and postoperative sensitivity. The data were collected, tabulated and statistically analyzed at a level of significance (P ≤ 0.05) using Friedman test, Chi-square and Fisher's exact test. ResultsRegarding the clinical performance of the tested materials there was no statistical significant difference among the different recall periods in all the tested criteria in both materials and no statistical significant difference between group I versus group II at all follow up periods (P > 0.05). In addition Kappa test revealed a statistical agreement between marginal discoloration as well as color match and both marginal integrity and surface roughness (P < 0.05). Conclusion1-The clinical performance of silorane based composite (Filtek P90) was deemed acceptable after one year; with no obvious advantage compared to methacrylate based composite. 2-The low shrinkage associated with (Filtek P90) may not be a determinant factor for its high clinical performance.

Effect of water storage on the translucency of silorane-based and dimethacrylate-based composite resins with fibres

ObjectivesThe purposes of this study were (1) to determine the translucency of silorane and dimethacrylate-based composite resins and (2) to evaluate the effect of water storage and reinforcement with fibre on the translucency of composite resins. MethodsTwo light-cured composite resins (A2 shade), Filtek Silorane (silorane-based composite) and Valux Plus (dimethacrylate-based composite), were used in this study. The first group was used as the control with no reinforcements, the second was reinforced with polyethylene (Ribbond THM) and the third was reinforced with a glass fibre (Everstick Net) for each composite resin. Colour measurements were measured against white and black backgrounds with a Shadepilot (Degu Dent Gmbh, Hanau, Germany) spectrophotometer and recorded under a D65 light source, which reflects daylight. CIELAB parameters of each specimen were recorded at baseline and at 24h, 168h and 504h. Translucency of materials was calculated using the translucency parameter (TP) formula. Data were analyzed using repeated measures ANOVA and LSD post hoc tests (α=0.05). ResultsThe highest baseline TP value was in the Valux Plus/non-fibre reinforced group (14.06±1) and the lowest in the Filtek Silorane/Ribond THM group (8.98±1.11). Repeated measures ANOVA revealed significant effects from the factors storage time, composite resin, composite resin×storage time and fibre×time (p=0.047; p=0.001; p=0.013; p=0.022, respectively). ConclusionWithin the limitations of the study, we concluded that inclusion of polyethylene and glass fibres did not alter the translucency of the different-based composite resins. The longest storage time resulted in the greatest change in translucency values of Filtek Silorane composite resins. Clinical significanceConsidering the translucencies of composites with different formulations in the selection of composite resins for aesthetic restorations is important in terms of obtaining optimal aesthetic outcomes.

The Influence of Zinc Oxide Eugenol (ZOE) and Glass Ionomer (GI) Base Materials on the Microhardness of Various Composite and GI Restorative Materials

Objective: Re-examining the well accepted concept that Zinc-Oxide-Eugenol bases (ZOE) have a negative effect on composite restoration materials microhardness, in light of the advancement in composite materials and newer publications. Methods: Five modern composite restoration materials were used, including hybrid (Xtra-fill and Z250), micro-fill hybrid (G-aenial and Gradia-direct) and methacrylate-free restorative material (Silorane- oxirane). Two base materials were used IRM (ZOE-base) and Fuji-IX (GI-base). Samples were made using a designed mold, in which composite discs were cured on top and in close relation to base materials. Micro-hardness testing was performed using a DMH-2 microhardness tester utilizing the Knoop method. Results: Statistic analysis demonstrated significantly better microhardness of three composite materials when IRM was used as base in comparison to control (G-aenial, Gradia direct and Filtek silorane), and no differences in two materials (Filtek universal Z250 and Voco Xtra-fil). Fuji-IX bases showed a significant positive effect on the microhardness of four composite materials, and a negative effect on one material (Voco Xtra-fill). In comparison with other tested restoration materials, both Voco Xtra-fill and Fuji-IX showed higher microhardness results (P<0.05).Significance: Related to microhardness, both ZOE and GI bases can be used safely as bases under composite restorations. The results of this study together with the results published recently showed that the concept of not using ZOE or GI bases under composite must be reconsidered. Fuji IX showed microhardness results similar to the best composite material and therefore it can be used as a restorative material.

Two methods to simulate intrapulpal pressure: effects upon bonding performance of self‐etch adhesives

To evaluate the effects of two methods to simulate physiological pulpal pressure on the dentine bonding performance of two all-in-one adhesives and a two-step self-etch silorane-based adhesive by means of microtensile bond strength (μTBS) and nanoleakage surveys. The self-etch adhesives [G-Bond Plus (GB), Adper Easy Bond (EB) and silorane adhesive (SIL)] were applied to flat deep dentine surfaces from extracted human molars. The restorations were constructed using resin composites Filtek Silorane or Filtek Z350 (3M ESPE). After 24 h using the two methods of simulated pulpal pressure or no pulpal pressure (control groups), the bonded teeth were cut into specimens and submitted to μTBS and silver uptake examination. Results were analysed with two-way anova and Tukey's test (P < 0.05). Both methods of simulated pulpal pressure led statistically similar μTBS for all adhesives. No difference between control and pulpal pressure groups was found for SIL and GB. EB led significant drop (P = 0.002) in bond strength under pulpal pressure. Silver impregnation was increased after both methods of simulated pulpal pressure for all adhesives, and it was similar between the simulated pulpal pressure methods. The innovative method to simulate pulpal pressure behaved similarly to the classic one and could be used as an alternative. The HEMA-free one-step and the two-step self-etch adhesives had acceptable resistance against pulpal pressure, unlike the HEMA-rich adhesive.

Influence of Different Staining Beverages on Color Stability, Surface Roughness and Microhardness of Silorane and Methacrylate-based Composite Resins

To investigate the influence of different staining beverages on color stability, surface roughness and microhardness of silorane and methacrylate-based composite resins. Three different composite resins (Filtek Silorane, Filtek P60, Filtek Supreme XT) were tested. Thirty cylindrical specimens (10 × 2 mm) per material were prepared and polished with a series of aluminum-oxide polishing disks. Each group was then randomly subdivided into three groups according to the test beverages: distilled water (control), cola and coffee. The samples were immersed into different beverages for 15 days. Color, surface roughness and microhardness values were measured by a spectrophotometer, prophylometer and Vickers hardness device respectively, at baseline and after 15 days. The data were subjected to statistical analysis. Immersion in coffee resulted in a significant discoloration for all the composites tested, although the color change was lower in Filtek Silorane than that of MBCs (p < 0.05). All the composites tested showed similar surface roughness changes after immersion in different beverages (p > 0.05). Besides coffee caused more roughness change than others. Immersion in coffee caused highest microhardness change in Filtek Supreme XT (p < 0.05). Cola and coffee altered, to some degree, the color, surface roughness and/or microhardness of the tested resin composites, depending on the characteristics of the materials.

Effect of Mechanical Surface Treatment on the Repair Bond Strength of the Silorane-based Composite Resin.

Background and aims. A proper bond must be created between the existing composite resin and the new one for successful repair. The aim of this study was to compare the effect of three mechanical surface treatments, using diamond bur, air abrasion, and Er,Cr:YSGG laser, on the repair bond strength of the silorane-based composite resin.Materials and methods. Sixty cylindrical composite resin specimens (Filtek Silorane) were fabricated and randomly divided into four groups according to surface treatment: group 1 (control group) without any mechanical surface treatment, groups 24 were treated with air abrasion, Er,Cr:YSGG laser, and diamond bur, respectively. In addition, a positive control group was assigned in order to measure the cohesive strength. Silorane bonding agent was used in groups 14 before adding the new composite resin. Then, the specimens were subjected to a shear bond strength test and data was analyzed using one-way ANOVA and post hoc Tukey tests at a significance level of P &0.05. The topographical effects of surface treatments were characterized under a scanning electron microscope.Results. There were statistically significant differences in the repair bond strength values between groups 1 and 2 and groups 3 and 4 (P &0.001). There were no significant differences between groups 1 and 2 (P = 0.98) and groups 3 and 4 (P= 0.97).Conclusion. Surface treatment using Er,Cr:YSGG laser and diamond bur were effective in silorane-based composite resin repair.

Solubility of two resin composites in different mouthrinses.

Aim. This study aimed to compare the solubility of a universal restorative resin composite (Filtek Z250; FZ250) and a silorane-based resin composite (Filtek Silorane; FS) after immersion in alcohol-containing mouthrinse, alcohol-free mouthrinse, and artificial saliva. Methods. 30 discs (10 mm × 1 mm) were prepared from each material and desiccated until a constant mass was obtained. Specimens were immersed in the test solutions for two days and desiccated again. Solubility was calculated based on the change in weight of each specimen before and after immersion. Data was analyzed using two-way ANOVA and Tukey's Post Hoc test (P < 0.05). Results. Solubility values for both resin composites were the highest in the alcohol-containing mouthrinse. FZ250 showed greater solubility than FS; the difference was only significant in artificial saliva. Conclusion. Both resin-composite materials tested exhibited some degree of solubility in each of the test solutions. The use of an alcohol-free mouthrinse may be preferable for patients with extensive composite restorations.

Effect of extraction media and storage time on the elution of monomers from four contemporary resin composite materials.

Introduction:The purpose of this study was to examine the effect of different extraction media, including culture media, as well as storage times on the elution of monomers from modern dental composites.Materials and Methods:Four contemporary composite materials were tested: (a) Clearfil Majesty Esthetic (Kuraray), (b) Esthet X (DENTSPLY), (c) Filtek Silorane (3M ESPE), and (d) Admira (Voco). Forty-eight specimens were made. The specimens were stored in 1 ml of (a) artificial saliva, (b) Dulbecco's Modified Eagle Medium (DMEM), (c) DMEM plus 10% fetal bovine serum (FBS), and (d) ethanol 75%. The specimens were analyzed after 24 hours and after 1 week of storage. HPLC Liquid Chromatography was performed to analyze the extracted solutions. The statistical package SPSS 18 was used for the statistical analysis of the results.Results:All the materials tested released monomers that were consistent with the base composition of their resin matrix. Bisphenol-A (BPA) was detected in Clearfil Esthetic and EsthetX when ethanol 75% was used for storage. TEGDMA was released at a faster rate compared to the other monomers with most of the monomer eluted in the first 24 hours. The effect of storage solution and storage time on the elution of the same monomers varied between materials.Conclusions:There was a significant effect of time, storage solution, and material on the elution of the detectable unbound monomers. Unbound monomers were detected in culture media, which may lead to false-negative results in cytotoxicity tests of resin composite materials. BPA was detected in two of the tested materials.

Caries detector dyes: Do they stain only the caries?

Objective: Caries detector (CD) dyes aid in caries diagnosis by staining the organic matrix of less mineralized infected dentine. However, detector dyes are not specific to bacteria and can discolor surrounding healthy tissues as dentino-enamel junction or the circumpulpal dentine. Possible discoloring effect of CD dye over restorative materials have not been evaluated until date. The aim of this study was to investigate the staining effects of four commercial CD dyes Caries Detector (CAD), Caries Marker (CAM),SEEK (SEE), Sable Seek (SES) on a variety of tooth colored restorative materials; Filtek Valux Plus (VLX), Filtek Z250 (Z25), Filtek Silorane (SIL) Fuji IX (FUJ). Materials and Methods: A total of 40 disc-shaped specimens were prepared from each restorative material. After 24 h distilled water storage, baseline color was measured according to the Commission International de l'Eclairage L* a* b* system by using a reflection spectrophotometer. Each CD dye was applied to 10 samples of each composite group for 10 s and applications were repeated for 2 times. Before the final color measurements, all samples was rinsed and dried. Color differences (ΔE) were measured and analyzed the data with two-way analysis of variance and Tukey honest significant difference post-hoc tests. Results: Independent of dyes, perceptible color changes were observed in glass ionomer restorative material (FUJ) (ΔE ab * > 3.3). CAD, CAM and SES caused staining on highly triethylene glycol dimethacrylate monomer containing composite resin (VLX). Silorane based restorative material (SIL) and micro hybrid resin composite (Z25) were more resistant to discoloration then VLX and FUJ (P < 0.05). Conclusion: CD dyes may cause discolorations in some restorative materials and should be used with maximum care.

Effect of Sodium Ascorbate and Delayed Bonding on the Bond Strength of Silorane and Two-step Self-etch Adhesive Systems in Bleached Enamel.

Background and aims. Studies have shown decreased bond strength of composite resin to human and bovine bleached enamel. This study evaluated the effect of sodium ascorbate and delayed bonding on the bond strength of two adhesive systems to bleached enamel.Materials and methods. The labial surfaces of 150 sound bovine incisor teeth were abraded with abrasive paper. The teeth were randomly divided into 8 groups: A: control; B: bleached with 35% hydrogen peroxide; C: bleached with 35% hydrogen peroxide + sodium ascorbate gel; and D: bleached with 35% hydrogen peroxide + delayed bonding. In groups A‒D, silorane adhesive system and Filtek silorane composite resin were used. In groups E‒H, the same preparation methods of groups A-D were used. Two-step self-etch Clearfil SE Bond adhesive systems and AP-X composite resin were administered. Shear bond strength of each group was measured. Two samples were prepared for each surface preparation for ultra-structural evaluation. Two-way ANOVA and Tukey test were used for data analysis at P<0.05.Results. The interaction between the adhesive system type and surface preparation protocol was significant (P=0.014), withsignificant differences in shear bond strengths in terms of the adhesive systems (P<0.01). There were significant differences in shear bond strength in terms of surface preparation techniques irrespective of the adhesive system (P<0.01).Conclusion. The results showed that bleaching with 35% hydrogen peroxide decreased the shear bond strength values with both adhesive systems, and a one-week delay in bonding and 10% sodium ascorbate for10 minutes restored the bond strength in both adhesive systems.

The Effect of a Modeling Resin and Thermocycling on the Surface Hardness, Roughness, and Color of Different Resin Composites

The application of modeling resin could affect the surface quality and color of resin composites. To evaluate the effects of modeling resin on the microhardness, roughness, and color of composite restorations, with and without thermocycling. Sixty disc-shaped specimens for each resin composite were prepared in three groups: Group 1: A resin composite disc was cured against a polyester matrix and finished/polished; Group 2: A composite instrument was wetted with Bisco Modeling Resin (Bisco, Schaumburg, IL, USA) to smooth the composite surface, which was cured against a polyester matrix and finished/polished; Group 3: A composite instrument was wetted with modeling resin to smooth the composite surface, which was cured against a polyester matrix. Microhardness, roughness, and color were measured 24 hours after curing and after 10,000 thermocycles. Modeling resin significantly influenced the microhardness of GrandioSO (Voco, Cuxhaven, Germany) and Gradia Direct Posterior (GC America, Alsip, IL, USA), and the surface roughness of GrandioSO, Filtek Silorane (3M ESPE, St Paul, MN, USA), and Aelite All Purpose Body (Bisco) (p < 0.05). The microhardness of the Group 1 resin composites was affected by thermocycling (p < 0.05); however, thermocycling had no significant effect on surface roughness (p > 0.05). Tested composites showed clinically perceptible color changes after thermocycling. In Group 1, Filtek Ultimate (3M ESPE) showed the lowest color change (p < 0.05), and in Group 2, Filtek Silorane showed the highest significant color changes (p < 0.05). Modeling resin did not affect the microhardness, surface roughness, and color of Aelite LS Posterior (Bisco), Filtek Ultimate (3M ESPE), and Clearfil Majesty Esthetic (Kuraray Medical Inc, Tokyo, Japan) specimens. Also, thermocycling process only affected microhardness of tested resin composites. The effect of modeling resin on surface microhardness, roughness, and color stability of composite materials depends on the type of resin composite. In clinical practice, the adverse effects of modeling resin might be alleviated by a proper finishing and polishing procedure.

Polymerization Shrinkage of Different Types of Composite Resins and Microleakage With and Without Liner in Class II Cavities

To determine the volumetric polymerization shrinkage of four different types of composite resin and to evaluate microleakage of these materials in class II (MOD) cavities with and without a resin-modified glass ionomer cement (RMGIC) liner, in vitro. One hundred twenty-eight extracted human upper premolar teeth were used. After the teeth were divided into eight groups (n=16), standardized MOD cavities were prepared. Then the teeth were restored with different resin composites (Filtek Supreme XT, Filtek P 60, Filtek Silorane, Filtek Z 250) with and without a RMGIC liner (Vitrebond). The restorations were finished and polished after 24 hours. Following thermocycling, the teeth were immersed in 0.5% basic fuchsin for 24 hours, then midsagitally sectioned in a mesiodistal plane and examined for microleakage using a stereomicroscope. The volumetric polymerization shrinkage of materials was measured using a video imaging device (Acuvol, Bisco, Inc). Data were statistically analyzed with Kruskal-Wallis and Mann-Whitney U-tests. All teeth showed microleakage, but placement of RMGIC liner reduced microleakage. No statistically significant differences were found in microleakage between the teeth restored without RMGIC liner (p>0.05). Filtek Silorane showed significantly less volumetric polymerization shrinkage than the methacrylate-based composite resins (p<0.05). The use of RMGIC liner with both silorane- and methacrylate-based composite resin restorations resulted in reduced microleakage. The volumetric polymerization shrinkage was least with the silorane-based composite.

Comparison of time-dependent changes in the surface hardness of different composite resins.

Objective:The aim of this study was to evaluate the change in surface hardness of silorane-based composite resin (Filtek Silorane) in time and compare the results with the surface hardness of two methacrylate-based resins (Filtek Supreme and Majesty Posterior).Materials and Methods:From each composite material, 18 wheel-shaped samples (5-mm diameter and 2-mm depth) were prepared. Top and bottom surface hardness of these samples was measured using a Vicker's hardness tester. The samples were then stored at 37°C and 100% humidity. After 24 h and 7, 30 and 90 days, the top and bottom surface hardness of the samples was measured. In each measurement, the rate between the hardness of the top and bottom surfaces were recorded as the hardness rate. Statistical analysis was performed by one-way analysis of variance, multiple comparisons by Tukey's test and binary comparisons by t-test with a significance level of P = 0.05.Results:The highest hardness values were obtained from each two surfaces of Majesty Posterior and the lowest from Filtek Silorane. Both the top and bottom surface hardness of the methacrylate based composite resins was high and there was a statistically significant difference between the top and bottom hardness values of only the silorane-based composite, Filtek Silorane (P < 0.05). The lowest was obtained with Filtek Silorane. The hardness values of all test groups increased after 24 h (P < 0.05).Conclusion:Although silorane-based composite resin Filtek Silorane showed adequate hardness ratio, the use of incremental technic during application is more important than methacrylate based composites.

Three-year randomized clinical evaluation of a low-shrinkage silorane-based resin composite in non-carious cervical lesions

The clinical suitability of low-shrinkage resin composites for class V cavities has not been investigated in vivo. The purpose of this double-blind randomized clinical trial was to compare the clinical performances of low-shrinkage resin composite Filtek silorane and nanoceramic resin composite Ceram X mono in non-carious cervical lesions (NCCLs) over 36 months. Two calibrated operators restored 144 NCCLs in 24 patients by using Filtek silorane with silorane system adhesive (FS/SSA) and Ceram X mono with Clearfil SE (CXM/CSE) or XP bond (CXM/XPB). Then, two blinded, calibrated evaluators assessed the restorations at the baseline and 6, 12, 24, and 36 months thereafter by using the modified US Public Health Service criteria. Data were analyzed with the Freidman and Wilcoxon signed-rank tests at a significance level of 5 % (P < 0.05). No restoration was associated with postoperative sensitivity or secondary caries. Further, no group showed significant changes until 12 months. The retention rates of the FS/SSA (97.5 %), CXM/CSE (97.5 %), and CXM/XPB (92.31 %) restorations did not differ significantly (P > 0.05). Six (4 CXM/XPB, 1 FS/SSA, and 1 CXM/CSE) of the 121 restorations evaluated at 36 months were completely lost. However, no significant intergroup differences were observed in the other evaluation criteria. The 3-year clinical performances of the restorative materials in NCCLs were not significantly different. Filtek silorane is suitable for restoring NCCLs.